1. Field of the Invention
This invention relates to musical performance apparatuses such as player pianos that perform feedback controls individually with respect to operators such as pedals and keys in accordance with performance information.
This application claims priorities on Japanese Patent Applications Nos. 2004-127143 and 2004-205039, the contents of which are incorporated herein by reference.
2. Description of the Related Art
Conventionally, various types of musical performance apparatuses such as player pianos have been developed and designed such that operators such as keys and pedals are individually driven by feedback controls based on displacements thereof in accordance with performance information, thus realizing automatic performance.
Japanese Patent Application Publication No. H06-214560 discloses time-sharing servo controls with respect to a musical performance apparatus, wherein in the precondition that generally-known player pianos are each limited to have sixteen tone-generation channels for simultaneously generating musical tones, time-sharing servo controls are performed on the limited number of actuators, which are selected and not actually used in musical practice within a plurality of actuators subjected to servo controls in parallel, whereby it is possible to reduce the load of servo processing and the number of circuits, thus realizing a simple constitution for controlling numerous actuators.
However, the aforementioned musical performance apparatus has the limited number of operators that can be simultaneously controlled; hence, it has difficulty in coping with simultaneous generation of numerous musical tones due to recent developments of technologies regarding electronic musical instruments. Strictly speaking, time-sharing processing (or time-division processing) may produce deviations regarding control timings for various operators. Such a problem may apparently occur as the number of operators is increased; hence, it is strongly demanded to further develop musical performance apparatuses in controlling numerous operators in real time.
U.S. Pat. No. 5,022,301 discloses a musical performance apparatus (namely, a reproducing piano) in which key drive data are produced based on performance data and are supplied to latch circuits via shift registers having steps corresponding to keys; then, the key drive data are applied to solenoids for driving keys by means of decoders in response to outputs of three pulse-width modulators (see FIGS. 1 and 7), wherein in the pulse-width modulator, a comparator compares a triangular wave generated by a triangular-wave generator and an output of a timing control circuit.
In the aforementioned musical performance apparatus, the timing control circuit requires a clock generator for determining the transfer timing regarding the key drive data, and the triangular wave generator also requires a clock generator in order to generate a triangular wave having a prescribed frequency.
That is, the performance control system of the aforementioned musical performance apparatus needs to have two ‘independent’ clock generators in order to realize automatic performance. This makes the performance control system complicated.
In addition, the performance control system may require a buffer in order to establish synchronization with respect to input/output operations regarding key drive data in the automatic performance that is realized based on independent clock signals. This causes relatively large delays between samples regarding performance controls, which may be therefore deteriorated in response and become unstable.